A high-performance application specific integrated circuit (ASIC) must be secure against a variety of dedicated attacks from unauthorized adversaries. One class of attack involves physically probing, modifying, or destroying the logic within the ASIC. This type of tampering usually involves several steps including, for example, (1) physically de-capping the package to have physical exposure to the wiring and logic on the silicon die; (2) boring holes into the surface protection layer to give access to metal contacts; (3) physically probing (while active) the wires at the top layer of the device to determine their content; (4) cutting top-level wires deemed to be unimportant in order to gain access to more interesting content on lower layers, possibly down to the base layer; (5) using a Focused Ion Beam (FIB) to cut wires to potentially turn off critical security features; and (6) depositing metal to create new connections to modify critical functionality.
Despite the numerous steps involved, unauthorized parties are becoming more sophisticated in their techniques for physically probing, modifying, and/or destroying the logic within ASICs. To protect against efforts to compromise the device's correct operation and functionality, it is important to have a physical security system that can detect any of the above activities while the chip is active, as well as detect upon start up if any of these activities occurred during the last power down period.